This project focuses on the design aspects of multicontract cochlear implants concentrating on the factors that affect their ability to be removed and replaced, possibly with dimensionally different implants. The new designs must cause minimal mechanical trauma and foreign body reaction in middle and inner ear structures. It is anticipated that this will include improvements in surface materials, electrode geometries and implant fixation techniques as compared with presently existing electrode arrays. Evaluation will be in non-deaf animal models of the developing child. The decision to use a non-deaf model is based on the fact that hair cells are sensitive indicators of disturbances of cochlear structure and function. Also, in deaf models with implanted electrode arrays, cochlear damage produced by inducing deafness complicates the interpretation of damage caused by the implant itself.